<br /><br />Do these engines have adjustable main jets or fixed main jets like most larger outboard engines? This would be in addtion to an adjustable idle mixture screw. Generally the things that make an engine run rich in order of likely hood are:<br />1. Stuck open carb floats<br />2. Leaking fuel pump diaphragms<br />3. Inaccurate main jet setting.<br /><br />If you have adjustable main jets I would move #3 to #1. If they are fixed I would verify with the dealer that they are correct and then verify that they are screwed in snug. There aren't that many ways for extra gas to get in there. Usually, not enough is the more common problem.<br /><br />Also the fuel for the idle circuit is initially controlled, I believe, by the main jet. So if the main jetting is screwed up, the idle setting will be screwed up. Sometimes people will over adjust the idle mixture to make up for incorrect main jet settings. Then the engine may idle but not work off idle. Get a manual and make sure your baseline settings are correct. If there is an adjustment for the main jet, get that right first before you start fiddling with the idle mixture.
